We have an instance of FileMaker Server 16.0.2 (on Windows Server 2012 R2) running multiple concurrent sessions of the same schedule that appear to be running concurrently, which is causing the creation of duplicate records.
It appears as if a first sessions starts, then immediately stalls, and the start of a second session also resumes the first, then they operate in such lock-step that adding find conditions to the scripting is not effective at avoiding the creation of duplicates. This is despite the fact that the schedule is configured to abort after 5 minutes. (The schedule is also configured to run every 5 minutes.)
Restarting fmse temporarily stops the duplicate sessions, but duplicate sessions resume after several hours.